Radioallergosorbent tests (RAST) are laboratory tests used to assess allergies to certain substances such as foods, inhalants, and medications. However, synonyms for RAST are also available, providing alternative terms for the same type of diagnostic tool. One such synonym is ImmunoCAP, which stands for Immuno (immunology) and CAP (capacity). ImmunoCAP is a widely used blood test that measures specific IgE antibodies, offering a reliable and sensitive method for determining allergies. This term is often used interchangeably with RAST since both tests serve the same purpose of evaluating and identifying allergic reactions. Thus, ImmunoCAP can be considered as a synonymous alternative to RAST when discussing allergy testing methods.